1. Field of the Invention
The present invention relates to improvements in a leader block rotary mechanism for a cartridge magnetic tape device.
2. Description of the Related Art
A leader block rotary mechanism for a cartridge magnetic tape device has a configuration in which a leader pin of the magnetic tape is captured or released by rotating the leader block. This type of the leader block rotary mechanism for a cartridge magnetic tape device is disclosed, for example, in Japanese Unexamined Patent Publication No. 2001-135003.
FIG. 1 and FIG. 2 show schematic views of the structure of a conventional leader block rotary mechanism and FIG. 3 and FIG. 4 show the operational principle. Specifically, FIG. 3 shows the leader block rotary mechanism from the top-face side and FIG. 4 shows it from the bottom-face side.
In the conventional leader block rotary mechanism, first, a leader block 13 is moved to be set in the capture position. In the set state, a groove 13-1 of the leader block 13 is to be engaged with a projection 14-1 of a retractor table 14 which is freely rotatable.
When capturing a leader pin of the magnetic tape by the leader block 13, the linear motion of a retractor cam 15 is converted to the rotary motion of a retractor table 14 by, as shown in FIG. 3A to FIG. 3C and FIG. 4A to FIG. 4C, pressing the retractor table 14 against the retractor cam 15 in the F direction in the figure. By this rotary motion, the leader block 13 engaged with the retractor table 14 is rotated. According to the series of operations, the leader pin of the magnetic tape is captured by a hook part 13-2 of the leader block 13.
Further, when releasing the leader pin from the hook part 13-2, the inverse operation is carried out. That is, the retractor cam 15 is moved in the direction opposite to the F direction so that the leader block 13 is rotated by the tensile force of a spring 16 energizing to rotate the leader block 13 in the release direction. Thereby, the hook part 13-2 of the leader block 13 is released from the leader pin of the magnetic tape.
In the above-described conventional art, the rotation angle of the leader block 13, which is necessary for capturing/releasing the hook part 13-2 to/from the leader pin of the magnetic tape, depends on the sliding stroke of the retractor cam 15. Therefore, there may cause mis-capture of the leader pin or damages on mechanism parts due to over/less rotation of the leader block 13 depending on how the sliding stroke of the retractor cam 15 is adjusted.
As for the capture operation, the retractor cam 15 is forcibly pressed against the protruded part of the retractor table 14 so as to convert the linear motion of the retractor cam 15 to the rotary motion of the retractor table 14. Thus, the excessive force generated at the time of converting the linear motion to the rotary motion cannot be absorbed. Hence, mechanism parts may be damaged when the rotation of the leader block 13 is stuck due to unexpected reasons.
Further, as for the release operation, the rotary motion for returning the leader block 13 to the original position relies only on the tensile force of the spring 16. Therefore, rotation of the leader block 13 is easily stuck so that there may be cases where the leader pin cannot be released.